# Why is the velocity of a jump on Mars the same as on Earth?

## Homework Statement

Good evening,
I have a homework where the question is "How high will person jump on Mars?"

v2 = 2.amars.h1
V2 = 2.g.h2

## The Attempt at a Solution

I know everything to solve it. I can solve it by h1 / h2 . In this created equation the only unknown is h1 so it's all cool. But why can I assume that v1 and V1 are the same? Why jump velocity on Mars is the same as on Earth? Aren't there any changes? For example lower strength of muscles due to different weight(force)? I know that maybe my question is completely stupid and I'm very sorry about it. I'm happy that I've atleast tried to find it out but I think that I can't figure out why the velocities are the same without your help.

PeroK

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jbriggs444
Homework Helper
2019 Award
But why can I assume that v1 and V1 are the same?
Because it is homework and one is expected to use models that are simplified to the point of being incorrect.

Tom.G and HAF
Because it is homework and one is expected to use models that are simplified to the point of being incorrect.
Thank you very much sir. Now everything makes sense to me. I really appreciate it!

haruspex
Homework Helper
Gold Member
Why jump velocity on Mars is the same as on Earth?
The assumption is that the work the legs can do is the same. There is also the issue of how the height of jump is defined, but vertical displacement of mass centre (from the crouch position) is the biophysical standard. So it is not really about take off speed. How is that defined? At the moment the feet leave the ground, the Martian jumper would have a greater speed, having done less work against gravity already.

Of course, it is not really true that the same work will be done. Muscles have a couple of limits - max force and max contraction rate - with a nonlinear response along the way.

The assumption is that the work the legs can do is the same. There is also the issue of how the height of jump is defined, but vertical displacement of mass centre (from the crouch position) is the biophysical standard. So it is not really about take off speed. How is that defined? At the moment the feet leave the ground, the Martian jumper would have a greater speed, having done less work against gravity already.

Of course, it is not really true that the same work will be done. Muscles have a couple of limits - max force and max contraction rate - with a nonlinear response along the way.
Aha. So for correctness should I solve it from equation m.g.h(1) = m.a.h(2) right?

PeroK
Homework Helper
Gold Member
There is also the issue of how the height of jump is defined, but vertical displacement of mass centre (from the crouch position) is the biophysical standard.
Or, you could refer to the rules of the Olympic Standing Jump, from 1912:

haruspex